electrolysis of aluminium oxide

• Why are metals more reactive than carbon extracted using electrolysis?

  They cannot be reduced by carbon
• What is the compound used to extract aluminium?

  Aluminium oxide
• What is the purpose of mixing aluminium oxide with cryolite?

  To lower the melting point
• What is the melting point of aluminium oxide?

  Around 2000° C
• What materials are the cathode and anode made of in the electrolysis setup?

  Graphite
• Why is graphite used for electrodes in electrolysis?

  It conducts electricity and has a high melting point
• What happens to aluminium ions at the cathode?

  They gain electrons to form aluminium atoms
• What is the half equation for the reaction at the cathode?

  $Al^{3+} +$$3e^- \rightarrow Al$
• What happens to oxide ions at the anode?

  They lose electrons to form oxygen atoms
• What is the half equation for the reaction at the anode?

  $O^{2-} \rightarrow \frac{1}{2}O_2 +$$2e^-$
• What do the oxygen atoms formed at the anode do?

  They pair up to form oxygen molecules
• Why must the anode be replaced regularly?

  It reacts with oxygen to form carbon dioxide
• What are the two reasons why producing metals by electrolysis is expensive?

  High energy for melting and electric current
• What is the process of extracting aluminium by electrolysis?

  1. Mix aluminium oxide with cryolite
  2. Apply electric current to molten mixture
  3. Aluminium ions move to cathode, gain electrons
  4. Oxide ions move to anode, lose electrons
  5. Oxygen atoms form and pair up to O2
• What are the key reactions occurring during the electrolysis of aluminium oxide?

  • At the cathode:
  • $Al^{3+} +$$3e^- \rightarrow Al$ (reduction)
  • At the anode:
  • $O^{2-} \rightarrow \frac{1}{2}O_2 +$$2e^-$ (oxidation)
• What are the properties of graphite that make it suitable for electrodes in electrolysis?

  • Good conductor of electricity
  • High melting point
  • Stable at high temperatures
• What is the significance of the melting point in the electrolysis process?

  • Lower melting point reduces energy costs
  • Allows easier handling of materials